overgrazing, deforestation, and soil erosion aggravated by drought are contributing to desertification; limited natural freshwater resources away from the Senegal, which is the only perennial river; locust infestation

Due to difference in city rankings taken from two data sources we are listing here both lists :According to Wolfram: Nouakchott; Nouadhibou; Kifah; Rusu; KayhaydiAccording to Geonames: Nouakchott; Nouâdhibou; Néma; Kaédi; Rosso